This invention relates to a jet boat and more particularly to an improved exhaust system for a watercraft and particularly a watercraft of the jet propelled type.
Watercraft are powered by internal combustion engines in a wide variety of manners. For example, the engine may be either an outboard mounted outboard motor or an inboard unit of either an inboard or outboard drive. In addition, many watercraft are powered by jet propulsion units which are, in turn, driven by internal combustion engines. In connection with all of these types of watercraft, there are problems in connection with the treatment of the exhaust gases. Particularly, it is important to provide an efficient discharge for the exhaust gases that will not create excess back pressure which can deteriorate engine performance but also effective silencing must be accomplished.
These problems are particularly acute in conjunction with jet propulsion units and watercraft powered by them. Two types of exhaust treatment have been proposed for discharge and silencing of exhaust gases from jet propelled watercraft. In one of these types of systems, the exhaust gases flow through one or more expansion chambers that are contained within the hull of the watercraft and then are discharge through the side of the hull at the forward end thereof. This type of arrangement does not always provide effective silencing and the discharge of the exhaust gases above the water at the forward portion of the hull gives rise to contamination or soot forming on the hull.
Another type of exhaust system for jet propulsion powered watercraft discharges the exhaust gases either into the tunnel in which the jet propulsion unit is contained, or into the water being discharge from the discharge nozzle of the jet propulsion unit. Although these types of exhaust systems avoid the unsightly contamination of the hull, there is still contamination of the hull, albeit under water and also the exhaust silencing is not fully effective.
It is, therefore, a principal object of this invention to provide an improved and simplified exhaust silencing system for watercraft.
It is a further object of this invention to provide an improved silencing system for a jet propelled watercraft.
It is a further object of this invention to provide an effective system for discharging the exhaust gases from the internal combustion engine of a jet propelled watercraft without contaminating the hull, without increasing back pressure and, at the same time, while achieving effective silencing.